Altering the arm angles of actors in shot footage?

I have an interesting challenge ahead and I'm scoping out the best way to tackle it. I was given some footage of a fight scene in which to add a lot of various effects including gunfire. A couple of the extras toward the end of the shot are milling about with their pistols held at too low an angle and the director wants them to be involved in the gunfire. That will involve raising their arms so they're shooting at least reasonably close to potential targets.

I expect I could roto this but first I wanted to explore whether there were some other more clever approaches. The contrast with the background in the shot isn't great so the roto will probably be a slog. If I go that route I figure I could puppet warp the cutout arm segments and backfill the scene with some stamping or masking.

Before I launch into this chore does anyone have some sparkling clever alternative methods I could play with? Many thanks in advance!

Depending on the background and how much you need to move the arms, you might get away with picking a square area including parts of the background and mesh warping the whole piece to move the arm in position. This could work if you have foliage or some other natural background, or make the cut-out piece along a corner in a wall or some such thing, i.e. as long as there is nothing that will look obviously distorted when distorted. That would save some time -- but feasibility depends on what's in the background.

That failing, do the roto approach. You might still want to use mesh warp instead of puppet tool for the arms after rotoing them out if there is motion in the arms. Puppet pin uses the transparency from the first frame, but mesh warp utilizes the full extent of the layer (you can precomp the layer to have a suitable amount of transparent space around the arm), giving you more leeway. You need clean plates tracked in place to hide the original arms.

Yeah, that sounds about right. The set is an old warehouse so there's a bunch of background details like windows and such that the arms are occluding. I'm going to try your warping suggestion but methinks the roto will be the way to go because of all the sharp edges involved. I think I'm just in denial. I've already made a slew of clean plates from using Mocha Pro on this scene to remove an errant camera guy—in fact I may use that tool to erase the original arms, too.

Good catch on the mesh warp; was just doing some 2D character animation on another project with puppet and had that plugin stuck in my head.